A method to detect Campylobacter species by culture in a food pathogen enrichment broth followed by tagged cocktail polymerase chain reaction and DNA strip was developed. When C. jejuni was detected, we measured mutation of amino acid position 86 in the GyrA gene, which is involved in quinolone resistance. The quinolone-resistant strains with GyrA mutation and quinolone-sensitive strains were clearly differentiated simply by measuring their Tm values after SYBR green real-time polymerase chain reaction. To detect Campylobacter from the enrichment broth and predict the quinolone resistance, these methods took only 1 hr.
Examination methods for coliform bacteria in jelly beverage and powdered beverage with solidified ingredients, and standard plate counts in powdered beverage with solidified ingredients were investigated. In the examination of coliform bacteria in jelly beverage using Japanese official methods for beverage and powdered beverage, it was demonstrated that gas production by Escherichia coli in 10 ml of double strength lactose broth with bromothymol blue (LB) with 10 ml of jelly beverage was incorrectly judged on occasion. Gas, however, was successfully trapped in 100 ml of LB instead of 10 ml of double strength LB. In the examination of the powdered beverage with solidified ingredients, 100-fold diluted homogenate were prepared instead of 10-fold diluted homogenate to weaken solidification because 10-fold diluted homogenate had a high solidification. For coliform bacteria examination, gas was successfully trapped in 100 ml of double strength LB with 100 ml homogenate, and the detection limit was the same as that by Japanese official methods. For standard plate count examination, it, however, was difficult to count the colonies by pour plate culture method, and more investigation is needed in the future.